1. Field of the Invention
This invention relates to an electronic apparatus, such as a portable computer, having a housing containing a built-in antenna board for radio communication, in particular, a structure for mounting an antenna board in a housing.
2. Description of the Related Art
Recent electronic apparatuses have a radio communication function, such as a radio LAN. According to these apparatuses, it is possible to transmit and receive data among plural electronic apparatuses around through wireless communication. Electronic apparatuses having a radio communication function have antennas for radio communication. To achieve stable communication, it is necessary to eliminate factors of obstacles to a radiation field from an antenna as much as possible, and enhance the efficiency of the radiation field.
For example, Jpn. Pat. Appln. KOKAI Pub. No. 2002-73210, Jpn. Pat. Appln. KOKAI Pub. No. 2002-172376, Jpn. Pat. Appln. KOKAI Pub. No. 2003-37431 disclose a conventional portable computer in which an antenna is installed in a display unit. The display unit has a display housing containing a liquid crystal display panel. The antenna is installed inside the display housing. The display housing is supported by a main unit having a keyboard, and is rotatable between a closed position and an opened position. In the opened position, the display housing rises from the main unit, and the antenna is located on an upper end of the display housing. Thereby, the antenna is held in the unobstructed state.
In recent portable computers, thinning of display housings has been promoted to enhance their portabilities. To achieve thinning of a display housing, the display housing is preferably formed of metal such as magnesium alloy. This can secure the strength of the display housing, while the display housing is thinned.
However, if a display housing is formed of metal, the antenna is surrounded by a conductor. Consequently, the radiation field from the antenna is obstructed by the display housing, and it is impossible to achieve a good antenna radiation characteristic.
Jpn. Pat. Appln. KOKAI Pub. Nos. 2002-196837 and 2002-232220 disclose a portable computer in which an antenna is contained inside a metal display housing. In the computer, an opening is formed in a part of the display housing corresponding to the antenna. The opening is covered with a nonconductive cover such as a synthetic resin. This prevents obstruction to the radiation field from the antenna, and deterioration in the radiation characteristic of the antenna.
However, in the above structure, a hole is bored in the display housing, and the cover made of synthetic resin also serves as a part of the display housing. This inevitably reduces the strength of the display housing.